One thing before people start posting, strategies are in the grand scheme of things, meant to accomplish a certain goal by executing it throughout battle (ex. The purpose of the strategy was to take Hill Alpha from Blue team before time was up).
Tactics are what you're probably talking about, actions taken by the team on the field to meet an immediate goal.

As for fighting a larger team, stealth is invaluable for evening the odds. How is the enemy team set up? Clumped together as a group, set up an ambush to take as many down in am instance. Split into separate groups, try picking one off at a time. This however depends on a lot of factors like your environment and such.

 

That could work but also depending on who is on the team as well if you got a stupid captian that could work without any flaws but if you got. a veteriN capt that's a prob

 

But if you are on the larger team And you do it on a smaller team it's almost a garounteed victory so you got to watch out because I beat people using their own tactics against them

 

If the team you are playing is more then 50% larger then your team, and has equal or better guns, then a good tactic is to set up a fortified position and then send a few people out to draw the other team in to the fortified position and get ambushed. Pretty much you send some people out as bait for an ambush